EVALUATION OF A RECOMBINANT 27-KDA OUTER-MEMBRANE PROTEIN OF COXIELLA-BURNETII AS AN IMMUNODIAGNOSTIC REAGENT

The 27-kDa outer membrane protein from eight strains of Coxiella burne tii was expressed in the pET-21c protein expression system. Two fusion proteins with molecular masses of 30 and 32 kDa were evident in all e ight of the recombinants by SDS-PAGE and immunoblotting, A protein hav ing an approximate size of 30 kDa was purified from the Escherichia co li lysates by one-step affinity purification. The utility of the purif ied recombinant protein in ELISA was also evaluated by testing its rea ctivity with human sera and comparing this reactivity with that of Nin e Mile phase II antigen. All of the 40 IF-positive serum samples were ELISA-positive for both the Nine Mile phase II and recombinant antigen s, and negative serum controls were negative for both antigens, These results suggest that ELISA with the 27-kDa recombinant antigen is a se nsitive and specific method for detecting anti-C, burnetii antibodies in human sera.